Hardware

Hi to all,
I've a problem with m0n0wall ver. 1.236 in a VMWare ESX 3.5 U4 VM: the VM has the same hardware characteristics as 1.3b18 version (Vmx file) but randomly the CPU goes up to 100% and the machine doesn't respond to any command (web administrative console included). To fix this problem I have to restart the VM via Virtual Center... after a short period of time the issue is diplayed again.
For me it's important use a consolidated version of m0n0wall, the beta release is not recommanded for my infrastructure. Does anyone have this kind of problem?
Thanks a lot for any suggestion,
Maurizio.